← All games

Hailstone

Halving · 30 levels

Grow coral from 1 with ×2 and (n−1)÷3.

How to play

1. Every number falls back to 1: halve it if even, else 3n + 1. Each number's path is a branch of coral.
2. Grow coral up from 1 by undoing those steps: ×2 bends left, (n − 1) ÷ 3 bends right (only when the answer is whole and odd).
3. Match the ghost branch, then reach every pearl using exactly the polyps you have. ↓ walks back down.

To reach a pearl, work forward from it: 52 → 26 → 13 → 40 → … → 1. Then build that list backwards. Two pearls often share a trunk, so follow one until the paths split.

Open Hailstone

Teeter, Tint and Echo Heist are free starters. Other games unlock through earned game choices or permanent packs. Your progress stays in the browser; optional sign-in saves it to your website account.